This giant slab of concrete is the Barrage d'Emosson, a 180m-high, 554m-wide and 9m-48.5m-thick dam in Martigny, Switzerland. Two power plants exploit the water stored behind the dam, but thousands of climbers have figured out how to exploit the front face. It happens to be the world's highest artificial climbing wall.

The insect-sized dots are noted French climber Jean-Christophe Lafaille and his wife, Katya. "There's an incredible impression of vacuum when you're out on the cement wall," climber and photographer Philippe Poulet said. "There's 60m of overhang on 13m of cant and a little village just 1,500m underfoot."

It may look like a feat reserved for Spiderman, but local mountain guides spent 600 hours fitting a climbing route (called Dévers Emossionnel) with artificial rock grips and metal bolts to protect climbers from falling. Skilled climbers can make the ascent in roughly two hours.